強度調控放射治療對子宮頸癌有效

作者：Roxanne Nelson  
出處：WebMD醫學新聞

　　November 20, 2009 — 使用強度調控放射治療(intensity-modulated radiation therapy，IMRT)有助於限制週邊正常組織的曝露，因而降低毒性，是子宮頸癌可行的治療選項之一。
　　
　　華盛頓大學醫學院的研究者在一篇線上發表於10月30日美國放射腫瘤學會雜誌(International Journal of Radiation Oncology, Biology, Physics)的新研究中指出，此方法也可產生較佳的結果。相較於未使用IMRT放射治療的病患，使用18F-螢光去氧葡萄糖正子攝影(PET)/電腦斷層導引IMRT治療的子宮頸癌病患，有比較好的存活以及與治療相關毒性的發生率較低。
　　
　　第一作者、華盛頓大學放射腫瘤科住院醫師Elizabeth Kidd醫師表示，我們認為使用IMRT是子宮頸癌治療的下一個合理步驟。許多其他骨盆腔惡性腫瘤，如前列腺癌、肛門癌和直腸癌，都有使用IMRT。
　　
　　她向Medscape Oncology表示，有些機構已經準備在臨床試驗外使用IMRT，在我們這裡，所有子宮頸癌病患都用IMRT治療。
　　
　　【領先優勢且有效】
　　Eleanor Harris醫師受Medscape Oncology之邀發表獨立評論時表示，Kidd醫師等人是婦科癌症治療的先驅，因此一研究而佔有領先優勢。
　　
　　佛羅里達坦帕Moffitt癌症中心放射腫瘤科臨床主任、乳房與婦科臨床研究小組負責人Harris醫師表示，這看起來有效，本研究顯示了對於IMRT的實際希望，看起來有較佳的控制率且減少毒性。子宮頸癌治療相當有毒性且閾值高於其他癌症，所以可以降低毒性的任何做法都很重要。
　　
　　她指出，雖然這些結果有效，但仍需要其他中心證實，理想上，應該有一個試驗，由其他中心來報告下一個好消息。
　　
　　【以IMRT改善結果】
　　該研究檢視了452名新診斷為子宮頸癌的病患，於1997年6月至2008年9月間，在華盛頓大學接受可治癒性根治性放射線治療。2005年3月之前，317名病患併用全骨盆腔和分區照射，使用的是該機構的「步進式光楔技術(step-wedge technique)」。
　　
　　由於機構政策改變，2005年3月之後，所有的子宮頸癌病患(這世代共有135人)接受PET-導引之IMRT，使用「偽步進式光楔強度調整(pseudo-step-wedge intensity modulation)」方式。所有病患的治療處方還包括體外射線和近接治療，世代中有85%同時接受化療。
　　
　　所有病患的平均追蹤期為52個月(範圍從5-117個月)。因為未使用IMRT的病患是在研究早期時，他們的追蹤期間比較長，平均在治療結束後72個月；IMRT病患最近的平均追蹤時間為22個月。
　　
　　在最後追蹤時，178名病患發生復發—IMRT組有39名病患(28.9%)、未使用IMRT組有139名病患(43.8%)。兩組的復發類型相似，多數病患是遠端復發，10%以下只有發生骨盆復發。兩個研究組之間的無復發存活差異未達統計上顯著意義(P= .0738)，不過，IMRT組顯示較佳的整體和特定原因存活(P值均<.0001)。
　　
　　在最後追蹤時，另外報告指出：
　　* 247名病患(91名IMRT組，156名未使用IMRT組)存活且無此疾病
　　* 51名病患(34名IMRT組，17名未使用IMRT組)存活但仍有此疾病
　　* 122名病患(5名IMRT組，117名未使用IMRT組) 死於子宮頸癌
　　* 28名病患(4名IMRT組，24名未使用IMRT組)死於併發症
　　* 4名病患(1名IMRT組，3名未使用IMRT組)死於治療相關毒性
　　
　　較高等級的副作用發生率在IMRT組也較低。等級3以上的胃腸和生殖泌尿併發症，IMRT組有6% (8名病患)，顯著低於未使用IMRT組的17% (54名病患) (P=.0017)。
　　
　　作者們指出，治療後的PET發現，IMRT組和未使用IMRT組的長期復發率和疾病特定存活率相似。Kidd醫師表示，我們繼續追蹤病患，因此，未來我們可以發表長期結果，不過，我們認為目前的研究已經清楚顯示，IMRT組比未使用IMRT組更減少毒性且復發率未惡化。我們先前的研究發表的是以治療後3個月的PET反應代表長期結果。
　　
　　研究者皆宣告沒有相關財務關係。
　　
　　Int J Radiat Oncol Biol Phys.。線上發表於2009年10月30日。  


Intensity-Modulated Radiotherapy Promising for Cervical Cancer

By Roxanne Nelson
Medscape Medical News

November 20, 2009 — The use of intensity-modulated radiation therapy (IMRT) has been shown to help limit exposure to surrounding normal tissue, thereby decreasing toxicity, and might be a feasible treatment option in cervical cancer.

In a new study, published online October?30 in the International Journal of Radiation Oncology, Biology, Physics, researchers from Washington University School of Medicine in St. Louis, Missouri, show that this approach also produced better outcomes. Cervical cancer patients treated with 18F-fluorodeoxyglucose positron emission tomography (PET)/computed tomography–guided IMRT had better survival and a lower incidence of treatment-related toxicity than patients treated with non-IMRT radiotherapy.

"We think the use of IMRT is the next logical step in the treatment of cervical cancer," said lead author Elizabeth Kidd, MD, a radiation oncology resident at Washington University. "Many other pelvic malignancies, such as prostate, anal, and rectal cancers, are using IMRT."

Some institutions might already be using IMRT outside of clinical trials, she told Medscape Oncology. "At our institution, all cervical cancer patients are treated with IMRT."

"Cutting Edge" and Promising

Dr. Kidd and her team are pioneers in the treatment of gynecologic cancers, and they are on the "cutting edge" with this study, said Eleanor Harris, MD, who was approached by Medscape Oncology for independent comment.

"It looks promising, and the hope for IMRT is exactly what this study is showing," said Dr. Harris, section chief of the Breast Gynecologic Clinical & Research Divisions and clinical director of radiation oncology at Moffitt Cancer Center in Tampa, Florida. "It looks like they may have better control rates and reduced toxicity. Therapy for cervical cancer is very toxic and the threshold is higher than for other cancers, so anything that will reduce toxicity is very important."

Although these results are promising, they do need corroboration from other centers, she added. "Ideally, there should be a trial, but the next best thing will be reports from different centers."

Improved Outcomes With IMRT

The study examined 452 consecutive patients with newly diagnosed cervical cancer who were treated with curative intent with definitive radiation from June 1997 to September 2008 at Washington University. Prior to March 2005, 317 patients were treated with a combination of whole-pelvis and split-field irradiation, using the institution's "step-wedge technique."

Following an institutional policy change, all cervical cancer patients treated after March 2005 (n?= 135 in this cohort) received PET-guided IMRT, using pseudo-step-wedge intensity modulation. The treatment regimen for all patients also involved external irradiation and brachytherapy, and 85% of the cohort received concurrent chemotherapy.

The mean follow-up for all patients was 52 months (range, 5 to 117 months). Because non-IMRT patients were treated during the earlier phase of the study, their follow-up was longer and averaged 72 months from the end of treatment; the average time for the most recent follow-up in IMRT patients was 22 months.

At the time of the last follow-up, 178 patients had developed a recurrence — 39 patients (28.9%) in IMRT group and 139 (43.8%) in the non-IMRT group. The pattern of recurrence was similar between groups, with the majority of patients experiencing distant recurrences and 10% or less developing a pelvic recurrence only.

The difference in recurrence-free survival between the 2 study groups did not reach statistical significance (P?= .0738), although the IMRT group showed better overall and cause-specific survival (P?< .0001 for both).

Also at the time of last follow-up, the researchers reported that:

247 patients (91 IMRT, 156 non-IMRT) were alive with no evidence of disease
51 patients (34 IMRT, 17 non-IMRT) were alive with disease
122 patients (5 IMRT, 117 non-IMRT) had died of cervical cancer
28 patients (4 IMRT, 24 non-IMRT) had died of intercurrent disease
4 patients (1 IMRT, 3 non-IMRT) had died from treatment-related toxicity.
The incidence of high-grade adverse events was also lower in the IMRT group. Grade?3 or higher gastrointestinal and genitourinary complications were experienced in 6% (8 patients) of the IMRT group, which was significantly lower than the 17% (54 patients) in the non-IMRT group (P?= .0017).

The posttreatment PET findings suggest that long-term recurrence rates and disease-specific survival will be similar for the IMRT and non-IMRT patients, the authors note. "We are continuing to follow the patients, so we could present longer-term outcomes in the future," said Dr. Kidd. "However, we think the present study clearly demonstrates decreased toxicity and no worse recurrence rates with IMRT than with non-IMRT. In previous research from our institution, we showed that the response on the 3-month posttherapy PET was a surrogate for longer-term outcome."

The researchers have disclosed no relevant financial relationships.

Int J Radiat Oncol Biol Phys. Published online October?30, 2009.